I. Field
The present disclosure relates generally to circuit, and more specifically to techniques for mitigating intermodulation distortion in a receiver.
II. Background
A wireless device in a wireless full-duplex communication system can simultaneously transmit and receive data for two-way communication. One such full-duplex system is a Code Division Multiple Access (CDMA) system. On the transmit path, a transmitter within the wireless device (a) modulates data onto a radio frequency (RF) carrier signal to generate a modulated signal and (b) amplifies the modulated signal to obtain a transmit signal with the proper signal level. The transmit signal is routed through a duplexer and transmitted via an antenna to one or more base stations. On the receive path, a receiver within the wireless device (a) obtains a received signal via the antenna and duplexer and (b) amplifies, filters, and demodulates the received signal to obtain baseband signals. The baseband signals are further processed to recover data transmitted by the base station(s).
The received signal may include various signal components such as a desired signal and jammers. Jammers are large amplitude undesired signals that are close in frequency to the desired signal. A portion of the transmit signal may also leak from the transmitter via the duplexer to the receiver. Since the transmit signal and the desired signal are typically at two different frequencies, the transmit leakage signal can normally be filtered out and does not pose a problem in itself. However, non-linearity in the receiver may cause mixing of the transmit leakage signal with itself and with the jammers, which may then result in intermodulation distortion that falls within the bandwidth of the desired signal. The intermodulation distortion that falls inband acts as additional noise that may degrade performance
There is therefore a need in the art for techniques to mitigate the deleterious effects of intermodulation distortion in a receiver.